Stylus for recording instruments



June 27, 1933 u. KOHLER 1,915,426

STYLUS FOR RECORDING INSTRUMENTS Fil June 14, 1952 Patented June y27, 1933 UNITED STATES PATENT OFFICE ULRICH IOHLER, Ol' BERN, SWITZERLAND, ASSIGNOR T0 HASLER A. G. VOBMALS TELEG i 2 IH KSTTTE VON G'. HASLEB., 0F BERN, SWITZERLAND STYLUS FOB; RECORDING INSTRUMENTS Application led June 14, 1982, Serial No.

This invention relates to styluses for recording instruments, particularly speedometers and the like.

In recording speedometers it is known to 5 feed the record strip over a plate having a groove'into which the strip is pressed by a stylus for making a mark, but the friction between strip and the stylus is thereby increased. For diminishing the friction it has been proposed to use a small wheel for making the record line instead of a pin or stylus. As such wheels cannot be moved in an axial direction more readily than a stylus or pin and could not produce continuous lines, they have not been largely used in practice.

This invention has for its object to provide an improved construction of stylus to which the above defects are not attached.

According to the invention the improved stylus has its point constituted by a rotatable ball. As the ball can readily rotate in all directions the frictionalY resistance in all Vdirections is diminished. For overcoming the frictional resistance between the paper strip and the stylus it is therefore of no importance which of these parts is driven by the clockwork of the speedometer. In proportion as this frictional resistance is diminished the energy stored in the main spring can be usefull used for lengthening the time the clockwor will run, or for increasing the performance of the same so that it is possible to obtain with the same clockwork records every quarter instead of every half hour during an equally long period.

One embodiment of the invention is diagrammatically illustrated by way of example in the accompanying drawing wherein a marking device or stylus is shown in longitudinal section.

Referring to the drawing, a sleeve 1 is tapered conicall at one end and screwthreaded interna y at its other end. A ball 2 constituting the point of the stylus is freely rotatable in the tapered end of the sleeve and bears against an abutment constituted by one end of a threaded pin 8 which is screwed from the rear into the sleeve 3 and has a head 4. A tubular holder 5 has a bore of two diam- 5" eters, its front reduced portion having the 617,213, and in Switzerland June 27, 1931.

part of lesser diameter. The sleeve 1 is longitudinally movable in the front ortion and is held in its front end position y a spring 7 which abuts against a plug 6 in the larger part of the holder 5. The action of the spherical end of the stylus on the record strip for forming the record mark is the same as with fixed points of styluses, but differs therefrom in that the friction on the paper strip is considerably less and therefore the resist- C0 ance to be overcome by the driving mechanism or clockwork is correspondingly smaller.

Owing to the arrangement of the ball 2 in a sleeve inserted into the holder 5 it is possible to keep the diameter of the ball very small and yet be able to regulate the recording pressure by means of a spring in the holder, so that even if a vehicle provided with the speedometer or tachometer is stationary for some time and consequently, the stylus moves to and fro on the same line of the paper strip which is also stationary, the strip is not cut through.

I claim 1. A stylus, comprisin `-\a tubular holder, an abutment in one en "thereof, a sleeve movable endwise in said holder, a spring bearing against said abutment and biasing said sleeve, a pin extending through the bore of said sleeve, and a freely rotatable ball disposed in the outer end of said sleeve and constituting the point of the stylus, the end of the pin being substantially flat and constituting a bearing for said ball.

2. A stylus comprising in combination a tubular holder having a two-diameter bore, an abutment at the end of the bore of larger diameter, a sleeve slidable endwise in the bore of smaller diameter, a headed screw inserted into the inner end of said sleeve and having its head in the bore of larger diameter, a ball that is freely rotatable in the outer end of said sleeve and bears against said screw and constitutes the point of the stylus, and a compression spring bearing against said 95 abutment and said head of the screw.

In testimony whereof I aix my signature.

ULRICH KOHLER. 

